Just ran some tests. Syncing eachway on taks, notes, calendar and cotnacts is fine.

Email.

Marking read on Outlook and Handheld replicated to the other okay
Delete on handheld and it deletes it on Outlook
Delete it on outlook and it DOESN'T delete on the blackberry.
Have tried keeping it in deleted items, and removing them. Nothing, been waiting an hour for one to go and it's still here.